IDX-PRO+VDI

[golfnut]

Thx for that Jim

[adventureswithjim]

As for coils in real life use with a stock White's build (I used this machine for years as a treasure hunter...it's a beast!)...any white's 6.59khz machine. I could swap with coin master, 5900 and 6900 series, any classic and SOME XLT coils. The XLT coils that did work showed a lower performance. Beware I BELIEVE there are 2 different Blue Max 950 coils...one for classic series and one for XLT/DFX. The absolute best performance was the BLACK Max 950...it's thiner and runs hotter than the Blue Max. You can also use Blue Max 400, 800, 950 and 1500. (4", 8" 9.5" and 15") Bounty Hunter coils do not work, though still a 6.59khz, they are missing a cap in the coil housing that IDX expects to be there...but IDX could be modified to match I bet. The 4" gold coil by bounty hunter is a very effective design for precision work in tough places. I have not tested swapping Prizim coils, though friends who have report problems with it, it's hit or miss. Most of the the Blue Max coils are still readily available through kellyco and they have some nice charts on coil compatibility. The Black Max 950 is out production and virtually impossible to find sadly.

One other note...I've read through 37 pages of this...so far...I see many, many people having inconsistant results, highly variable performance...White's itself had consistancy issues! My machine was very, very senistive and very stable, I could easily locate targets of small coins over 10" deep and with the Blue Max 1500...small coins to 15", larger coins to 20". Yet other people I know who purchased the machine had very DIFFERENT results. Mine was stock, no Mr. Bill mods...and with that kind of performance, I simply wasn't going to screw around with it.

But over the decades of treasure hunting, there's one thing I've learned: depth is basically irrelevent. This is a gimmick the companies use to get people to buy the next model machine. Most VLF machines can hit 6" to 10" range, the real difference is in target seperation and working with iron. I think the IDX is an ideal platform for the VDI mods (which are awesome!) I have so many ideas to refine the IDX...getting ready to order parts, this thread is amazing for a true understanding of VDI and how IDX circuit actually works, thanks to everyone!

[golfnut]

try a whites coil on it. i think the coinmaster or IDx are similar coils - can anyone confirm.


What are the resistance readings on your CZ coil.
Are you certain you have the Tx coil wired to your Tx

When you did a12v mod, did you cut the 8v feed on the pcb the the Tx transistor and add a local decoupler of about 0.1uF

If this mod isnt really working with your coil revert back to original design and splash out on a whites coil for it. Same as Koala





Or make a coil up - bit of a faff though

S

[Koala]

Somewhere on this thread silverdog was hooking up a CZ coil and questioned to caps quoted earlier in the thread as maybe wrong. They got it sorted but they have an oscilloscope and the cap values not posted. Post 766 asks but can't find repliy and post 407 requires an oscilloscope. . If you get not response to a PM to Ivconic silverdog or eduardo1979. Think using an oscilloscope might be your only option if you can beg or borrow one

[gtdavid]

Yea mine is the 10.5 fisher cz
Yours makes mine look bad :-(

[Koala]

My nearest coin is 2p just under 26mm diameter just under 2mm thick and either copper or iron clad. Both iron and copper same distance 26.5cm same in disc and PP mode. Using 16 ohm headphones can get another cm in PP mode with 8 ohm speaker next to my ear. Disc mode nice clear tone is to 24 cm last 2.5cm broken dirty tone. That's with a standard whites 8" coil and no modificaions on a silverdog PCB. I take it is the 10.5" coil you have.

[gtdavid]

can some one please tell me what is the best way to run tx from 12v
please

[gtdavid]

ok i have retested with a au $1 coin 24mm round.
26cm

[Koala]

I have noticed a difference since disconnecting the 12v from the tx .
Testing with a small ring.
With 12v tx - 23cm
With standard 8v tx - 17cm
Still not to shore about why the transistor was getting hot. How do you run your tx at 12v?
And also I made a 2 tone board on a prototype board and I got a high pitch hum from the bc327.
This may be my bad prototype board or could it be a problem on my pcb? ?
Thanks

Hi can you test with a coin and I will test with mine and a 8" coil and compare. Distance with rings can vary a lot. Type of gold, size, shape.

[gtdavid]

I have noticed a difference since disconnecting the 12v from the tx .
Testing with a small ring.
With 12v tx - 23cm
With standard 8v tx - 17cm
Still not to shore about why the transistor was getting hot. How do you run your tx at 12v?
And also I made a 2 tone board on a prototype board and I got a high pitch hum from the bc327.
This may be my bad prototype board or could it be a problem on my pcb? ?
Thanks

[golfnut]

I would leave making this mod for now mate until you can prove you need it.

I dont need to alter anything and nothing gets hot.


If your air tests are a bit short and your not happy try someone elses coil or a coinmaster or idx coil

should do 7" in ground with small coin fairly easy with disc rejecting iron.

S

[gtdavid]

ok it appears that running the tx circuit at 12v volts was the cause of the bc327 overheating..
i tried to upgrade the bc327 with a bd140-16 that worked but still overheated.
is there a one that you use when running tx at 12v ?
and also just to make shore the rx tank cap is one you place in parallel over the rx wires? or is it the 220n that i replace?

[gtdavid]

hello,
i have just noticed that the bc327 is running hot on my board is this normal?
i have checked the leg arrangements and they are correct.

[golfnut]

I would try your kit on the ground now as your off first base, get used to all of the controls on your soil types. Getting the ground bal set properly and lowering sens position to max sens to targets but keep geb falses to minimum.



If it still isnt what you want, then do a few tweaks.



I run my Tx from 12v direct, it gives a more punchy hit on small targets - more than depth improvements. I have two batteries in my IDX 12v and 8v with a toggle switch for 12v or 20v tx supply


Most Tx tweaks for me where only a small improvement - often the difference between a one way tone and a two way tone - in use in the ground - tested on my testbed.


The most useful gain sensitive tweaks are the Rx tank tuning as you are looking at. Dont have the Rx tank resonate too close to the Tx freq or it will false a lot over the ground.

Generally,,
#
lots of turns on Rx coil - more Rx volts
GEB fine tune regularly
keep sens and threshold set accordingly
dont have the disc set beyond iron cut off - or you will loose a fair bit of depth
try more than one set of cans - borrow some others and some give user better info
good sheilding on the coil helps with falsing on wet grass

S

[gtdavid]

So far I have the cz connected and detecting a small ring at about 15-20 cm and a gold bracelet at about 20-25 cm .
I have put 33.3 n worth of caps on the rx (2*15n & 1*3.3n) I have seen a silght improvement .
I am thinking about boisting voltage on the tx line by hot wireing the tx ciruct direct to 12v as I have seen some one else do in this thread.
Thorghts?
Thanks.